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महाराष्ट्र राज्य शिक्षण मंडळएचएससी विज्ञान (सामान्य) इयत्ता १२ वी

State the mathematical relation between a number of turns in the primary coil to a secondary coil in the step-up transformer.

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प्रश्न

State the mathematical relation between a number of turns in the primary coil to a secondary coil in the step-up transformer. 

एका वाक्यात उत्तर
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उत्तर

In a step-up transformer, the number of turns in the secondary coil is more than that in the primary coil (NS > NP).   

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पाठ 12: Electromagnetic Induction - Very Short Answer

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संबंधित प्रश्‍न

State the principle on  which transformer works.


A transformer converts 240 V AC to 60 V AC. The secondary has 75 turns. The number of turns in primary are _______.

(A) 600

(B) 500

(C) 400

(D) 300

 


State the principle of the step-down transformer and its working.


Find the ratio of primary and secondary currents in terms of turn ratio in an ideal transformer.


How much current is drawn by the primary of a transformer connected to 220 V supply when it delivers power to a 110 V − 550 W refrigerator?


Name the transformer used in the power transmitting station of a power plant.


The following diagram in Fig. 10.44 shows a coil X connected to a sensitive centre –zero galvanometer G and a coil P connected to a battery through a switch S.

(a) Describe the observation when the switch S is (i) closed suddenly, (ii) then kept closed, (iii) finally opened.
(b) Name and state the law which explains the above observations.


What is the function of a transformer in an a.c. circuit? How do the input and output powers in a transformer compare?


Draw a labeled diagram of a full wave rectifier circuit. State its working principle. Show the input-output waveforms ?


Describe briefly, with the help of labelled diagram, working of a step-up transformer.

A step-up transformer converts a low voltage into high voltage. Does it not violate the principle of conservation of energy? Explain.


An a.c generator generates an emf 'ε' where ε = 314 Sin (50πt) volt. Calculate the frequency of emf ε.


In an ideal transformer, an output of 66 kV is required when an input voltage of 220 V is available. If the primary has 300 turns, how many turns should the secondary have?


Copy the given diagram of a transformer and complete it. Name the parts A and B. Name the part you have drawn to complete the diagram. What is the material of this part? Is this transformer a step-up or step-down? Give reason.


The power supply to the primary coil of a transformer is 200 W. Find
(i) Current in primary coil if the e.m.f. supply to it is equal to 220V.
(ii) The number of turns in the primary coil is equal to 80 and that in secondary is 800. What is the transformation ratio?
(iii) Name the type of transformer.
(iv) What will be the output voltage?
(v) What is the current in the secondary coil for an ideal transformer?
(vi) What is the output power?
(vii) Is output and input power equal?
(viii) Compare the current flowing in a secondary coil and in a primary coil.


The primary coil of a transformer has 200 turns while the secondary coil has 1000 turns. What type of transformer is this? if the input voltage is 10V, what will be the output voltage?


A transformer lowers e.m.f. from 220 V to 15 V. If 400 W power is given in primary, calculate (i) the current in primary coil and (ii) the current in secondary coil.


Transformer works on ______.


A step-down transformer reduces the supply voltage from 220 V to 11 V and increase the current from 6 A to 100 A. Then its efficiency is


Explain the construction of transformer.


Give the advantage of AC in long distance power transmission with an illustration.


Find out the phase relationship between voltage and current in a pure inductive circuit.


A step-down transformer connected to the main supply of 220 V is used to operate 11V,88W lamp. Calculate

  1. Voltage transformation ratio and
  2. Current in the primary

A 200V/120V step-down transformer of 90% efficiency is connected to an induction stove of resistance 40 Ω. Find the current drawn by the primary of the transformer.


The 300 turn primary of a transformer has resistance 0.82 Ω and the resistance of its secondary of 1200 turns is 6.2 Ω. Find the voltage across the primary if the power output from the secondary at 1600V is 32 kW. Calculate the power losses in both coils when the transformer efficiency is 80%


A power transmission line feeds input power at 2300 V to a stepdown transformer with its primary windings having 4000 turns. What should be the number of turns in the secondary in order to get output power at 230 V?


Quantity that remains unchanged in a transformer is ______.

Read the following paragraph and answer the question:


Long distance power transmissions

The large-scale transmission and distribution of electrical energy over long distances is done with the use of transformers. The voltage output of the generator is stepped up. It is then transmitted over long distances to an area sub-station near the consumers. There the voltage is stepped down. It is further stepped down at distributing sub-stations and utility poles before a power supply of 240 V reaches our homes.

We need to step-up the voltage for power transmission, so that ______.


Name one electrical device which works on Faraday's law of electromagnetic induction principle.


The primary winding of a transformer has 100 turns and its secondary winding has 200 turns. The primary is connected to an a.c supply of 120 V and the current flowing in its is 10 A. The voltage and the current in the secondary are ______.


A step-down transformer connected to an ac mains supply of 220 V is made to operate at 11 V, 44 W lamp. Ignoring power losses in the transformer, what is the current in the primary circuit?


A step down transformer connected to an ac mains supply of 220 V is made to operate at 11 V, 44 W lamp. Ignoring power losses in the transformer, what is the current in the primary circuit?


For an LCR circuit, the power transferred from the driving source to the driven oscillator is P = I2Z cos φ.

  1. Here, the power factor cos φ ≥ 0, P ≥ 0.
  2. The driving force can give no energy to the oscillator (P = 0) in some cases.
  3. The driving force cannot syphon out (P < 0) the energy out of oscillator.
  4. The driving force can take away energy out of the oscillator.

The line that draws power supply to your house from street has ______.

  1. zero average current.
  2. 220 V average voltage.
  3. voltage and current out of phase by 90°.
  4. voltage and current possibly differing in phase `phi` such that `|phi| < pi/2`.

Draw the effective equivalent circuit of the circuit shown in figure, at very high frequencies and find the effective impedance.


A 60 W load is connected to the secondary of a transformer whose primary draws line voltage. If a current of 0.54 A flows in the load, what is the current in the primary coil? Comment on the type of transformer being used.


A transformer operating at primary voltage 8 kV and secondary voltage 160 V serves a load of 80 kW. Assuming the transformer to be ideal with purely resistive load and working on unity power factor, the loads in the primary and secondary circuit would be:


In a transformer, number of turns in the primary coil are 140 and that in the secondary coil are 280. If current in primary coil is 4 A, then that in the secondary coil is ______.


Two coils P and Q are kept near each other. When no current flows through coil P and current increase in coil Q at the rate 10A/s, the emf in coil P is 15mV. When coil Q carries no current and current of 1. 8A flows through coil P, the magnetic flux linked with the coil Q is ______.


An iron rod is placed parallel to magnetic field of intensity 2000 Am-1. The magnetic flux through the rod is 6 × 10−4 Wb and its cross-sectional area is 3 cm2. The magnetic permeability of the rod in Wb A-1m-1 is ______.


Magnetic flux passing through a coil is initially 4 × 10-4 Wb. It reduces to 10% of its original value in t second. If the emf induced is 0. 72 mV then t in second is ______.


Mention two main sources of power loss in real transformers.


The large scale transmission of electrical energy over long distances is done with the use of transformers. The voltage output of the generator is stepped-up because of ______.


Derive the equation for a transformer.


A 12 V, 60 W lamp is connected to a 220 V AC supply using an ideal transformer. Find the primary current.


On the basis of winding, what are the two types of transformers?


How is the laminated soft iron core made?


What does the primary coil draw from the source?


Which description of the secondary coil is correct?


What does the secondary coil deliver to the circuit?


Where is alternating voltage \[V_p\] applied?


Which law relates the changing flux to the EMF induced in both coils?


What is the induced EMF in the primary coil?


What is the induced EMF in the secondary coil?


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